Ep. 02 - Fall Colors

Ep. 02 - Fall Colors

The Field Guides

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Episode Notes:

When discussing branching, Steve and Bill wondered whether Horsechestnut (Aesculus hippocastanum) was native. While some members of this genus are native to North America, the Horsechestnut (AKA Horse-chestnut or Conker Tree) is an imported species native to the Balkans.

Mistakes: 

     Steve had mentioned that there was only one genus in the Aceraceae, or maple family. This is wrong. That fool neglected the two species within the genus Dipteronia that are endemic to mainland China.

      Additionally, Steve also said, “we’ve slowly been knocking out all these different genes that code for all these different hormones”, which may have been misleading. Plant hormones are not transcribed directly from DNA; instead they are later synthesized by the products of specific genes. If the genes responsible for the synthesis of a particular hormone are “knocked out,” the plant will no longer be able to synthesize that hormone.             

         Also when Bill was describing how the abcisssion layer forms, he said that the separation layer gets thicker and pushes against the separation layer. What he meant to say was that the protection layer (the layer closer to the twig) gets thicker and pushes against the separation layer (the layer closer to the leaf). Here is a more complete description of the process: 

Abcission cells start to collect where the stem meets the branch. Two layers form – the separation layer and a protection layer. In the separation layer, the cells are short with thin walls. So, this area becomes weak and a tear starts to form. The protection layer is closer to the tree – a kind of nodule starts to grow. It cuts off all water and nutrients to the leaf, and, as the nodule grows, it pushes the leaf farther and farther from the branch until the separation layer is so brittle, it breaks. 

Work Cited: 

Anderson, Rachel, and Peter Ryser. "Early Autumn Senescence in Red Maple (Acer rubrum L.) Is Associated with High Leaf Anthocyanin Content." Plants 4.3 (2015): 505-522.

Archetti, Marco, et al. "Unravelling the evolution of autumn colours: an interdisciplinary approach." Trends in Ecology & Evolution 24.3 (2009): 166-173.

Archetti, Marco. "Phylogenetic analysis reveals a scattered distribution of autumn colours." Annals of botany (2009). 

Archetti, Marco. "Classification of hypotheses on the evolution of autumn colours." Oikos 118.3 (2009): 328-333.

Bolser, Jessica A., et al. "Birds select fruits with more anthocyanins and phenolic compounds during autumn migration." The Wilson Journal of Ornithology 125.1 (2013): 97-108.

Döring, Thomas F., Marco Archetti, and Jim Hardie. "Autumn leaves seen through herbivore eyes." Proceedings of the Royal Society of London B: Biological Sciences 276.1654 (2009): 121-127.

Estiarte, Marc, and Josep Peñuelas. "Alteration of the phenology of leaf senescence and fall in winter deciduous species by climate change: effects on nutrient proficiency." Global change biology 21.3 (2015): 1005-1017.

Habineck, E. M. "Correlation of soil development and landscape position with fall leaf colors." 2007 GSA Denver Annual Meeting. 2007.

Hamilton, William D., and S. P. Brown. "Autumn tree colours as a handicap signal." Proceedings of the Royal Society of London B: Biological Sciences268.1475 (2001): 1489-1493.

Hüner, Norman PA, and William G. Hopkins. "Introduction to plant physiology." (2008).

Killingbeck, Keith T. "Nutrients in senesced leaves: keys to the search for potential resorption and resorption proficiency." Ecology 77.6 (1996): 1716-1727.

Landi, M., M. Tattini, and Kevin S. Gould. "Multiple functional roles of anthocyanins in plant-environment interactions." Environmental and Experimental Botany 119 (2015): 4-17.

Lee, David W., et al. "Pigment dynamics and autumn leaf senescence in a New England deciduous forest, eastern USA." Ecological Research 18.6 (2003): 677-694.

Lev‐Yadun, Simcha, and Jarmo K. Holopainen. "Why red‐dominated autumn leaves in America and yellow‐dominated autumn leaves in Northern Europe?."New Phytologist 183.3 (2009): 506-512.

Schaefer, H. Martin, and David M. Wilkinson. "Red leaves, insects and coevolution: a red herring?." Trends in ecology & evolution 19.12 (2004): 616-618. 

Schippers, Jos HM, et al. "Living to die and dying to live: The survival strategy behind leaf senescence." Plant physiology 169.2 (2015): 914-930.

Taylor, Gail, et al. "Future atmospheric CO2 leads to delayed autumnal senescence." Global Change Biology 14.2 (2008): 264-275.

Ep. 01 - Goldenrod Galls

Ep. 01 - Goldenrod Galls

The Field Guides

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Answers to Questions That Arose During the Podcast:

1. Is an inquiline the same thing as a parasite?

Sometimes yes, sometimes no, and, sometimes, we can’t be sure. An inquiline is an animal that lives habitually in the nest or abode of some other species. When an inquiline harms the other species in any way, it is a parasite. If, however, its presence does not have a detrimental effect on the other species, the relationship would be commensalistic (a symbiotic relationship in which one species is benefited while the other is unaffected), not parasitic. At times, this distinction can be difficult to determine; in may instances, it can be hard to say if, and to what degree, an inquiline’s presence is harming the other species.

2. What is the life cycle of the Goldenrod Bunch Gall midge, Rhopalomyia solidaginis?

            During my initial research for this episode, I could find only vague references to the life cycle of the insect responsible for the Goldenrod Bunch Gall. When I finally did track down a source that shed some light, I was left wondering if those other authors left out the details for the sake of simplicity. While the Eurosta fly that makes the Goldenrod Ball Gall has an elegant, year-long life cycle that is easy to wrap your head around, the Rhopalomyia midge leads a life that’s tougher to follow. I had to reread the account several times before it started to make sense. Here’s how it appears to break down:

            The first thing to keep in mind is that the Rhopalomyia midge is bivoltine, which means that it produces two broods in one year, and each brood produces different galls on Goldenrod. Larvae hatch from eggs in the fall and burrow into rhizomes (underground stems), where they overwinter. In the spring, these larvae produce small bunch galls on emerging stems that are difficult to tell apart from stems without galls. This generation pupates in mid-spring. Then, the adults emerge, mate, and lay eggs on more Goldenrod plants.

This second generation creates the larger bunch galls that are seen on Goldenrod starting in mid-June. The larvae live in the base of the gall, within a chamber surrounded by very short and narrow leaves, and those leaves are surrounded by longer and wider leaves. Pupation takes place in early September, and adults emerge in September and early October to mate, lay eggs, and start the process all over again.   

Source: http://www.mapress.com/zootaxa/2009/f/zt02152p035.pdf, pg. 30-31

Links

This episode just scratches the surface of the world that is goldenrod galls. Check out goldenrod gall enthusiast Daniel McClosky’s effort to catalog all the gall-making insects on goldenrods.

Work Cited:

Cunan, Ellery T., Thomas HQ Powell, and Arthur E. Weis. "Evidence For Plant-mediated Competition Between Defoliating and Gall-forming Specialists Attacking Solidago altissima." The American Midland Naturalist 173.2 (2015): 208-217.

Hartnett, David C., and Warren G. Abrahamson. "The effects of stem gall insects on life history patterns in Solidago canadensis." Ecology (1979): 910-917.

Mapes, Carol C., and Peter J. Davies. "Cytokinins in the ball gall of Solidago altissima and in the gall forming larvae of Eurosta solidaginis." New Phytologist 151.1 (2001): 203-212.

Eastman, John Andrew. The Book of Field and Roadside: Open-Country Weeds, Trees, and Wildflowers of Eastern North America. Stackpole Books, 2003.

Messina, Frank J. "Plant protection as a consequence of an ant-membracid mutualism: interactions on goldenrod (Solidago sp.)." Ecology (1981): 1433-1440.

Newcomb, Lawrence. "Newcomb’s wildflower guide." Little, Brown, and Company, Boston. xxii (1977).

Peterson, Roger Tory, and Margaret McKenny. A field guide to wildflowers: northeastern and north-central North America. Houghton Mifflin Harcourt, 1996.

Stokes, Donald. “A Guide to Nature in Winter.” Little, Brown and Company, 1976.

Wise, Michael J., Warren G. Abrahamson, and Julia A. Cole. "The role of nodding stems in the goldenrod–gall–fly interaction: A test of the “ducking” hypothesis." American journal of botany 97.3 (2010): 525-529.